NATS can saturate a network port with hundreds of thousands of messages/second with minimal impact on CPU, it scales linearly with cores, and it has minimal/zero effort fail-over. Whether across large geographic boundaries (ie: AWS cross-region) or in the same rack, NATS clustering is reliable and definitely speedy.
Well said; the other project involving NATS from the Rapidloop team (gRPC over NATS essentially) mentions some benefits as they see it which are what you've pointed out: https://github.com/rapidloop/nrpc